Conventionally, pilots use weather radar to detect and then avoid hazardous weather. Conventional radar systems may produce the desired results only in a limited environment. Typically, airborne threshold systems are traceable to ground-based weather radar thresholds for wet precipitation generated from convective weather. Such thresholds have been set in accordance with reflectivity data which is applicable to typical convective weather systems in continental environments but not necessarily in maritime regions. It has been observed that maritime storm reflectivity differs substantially from continental storm reflectivity. Research by Zipser and Lutz in “The Vertical Profile of Radar Reflectivity of Convective Cells: A Strong Indicator of Storm Intensity and Lightning Probability?”, Monthly Weather Review of the American Meteorological Society, 1751–1759 (August 1994), characterizes the differences in reflectivity of continental versus maritime convective storms. Below the freezing altitude, the research shows that maritime storm reflectivity averages 8 dB below that of continental storms with peak maritime reflectivities observed at near sea level while peak continental reflectivities are observed at about the 8000 foot region. Above the freezing altitude, the reflectivity of maritime cells falls off at an average rate of 1.4 dB per 1000 feet versus the falloff rate of 0.45 dB per 1000 feet for continental storms. Peak reflectivity differences between the two populations of cells peak at about the 23 dB range at about 28,000 feet.
Conventionally, radar thresholds map radar return strength to a display with color representing rain rate or alternatively a weather threat assessment level. The threat level has been previously described as primarily a function of radar reflectivity and a weaker function of temperature, altitude, and latitude. However, because of the difference in maritime and continental weather, the conventional mapping while useful, does not completely allow successful operation of aircraft in maritime regions. The lower reflectivity of maritime weather does not allow for successful detection of significant convective weather systems during flight. Further, because of the ability of aircraft flying over maritime regions to circumnavigate storm systems, if recognized, it would therefore be desirable to provide an airborne radar system which has the ability to more accurately detect and report the existence and/or characteristics of maritime storms when operating in maritime environments and continental storms when operating in continental environments. It may be possible for a pilot operating radar manually to be able to compensate for the differences in maritime and continental weather as each pilot becomes familiar with the environment. However, knowledge by the pilot must be acquired, and further, an increase in pilot workload is also necessitated. Therefore, there is a need for an automated system of adjusting radar thresholds based on the presence of maritime or continental weather environments.
Often, the reflectivity of maritime weather systems may be lower than that which may be detected with the conventionally used on-board radar hardware. Accordingly, there is a need for an automated system that adjusts radar tilt, to improve detectability of weather systems in maritime environments.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.